What does “sequester” mean in English?

You have probably seen “sequester” in science news about climate. But the same word turns up in law and politics too. It always means the same thing: take something out, keep it apart, lock it away. In this clip, a marine biologist uses it to describe what tiny ocean plants do to carbon dioxide — they pull it from the air and hold it deep underwater, where it cannot warm the planet.

In the clip, the scientist explains how phytoplankton — tiny ocean plants — use sunlight to grow, and as they grow they pull carbon dioxide from the air. She says: “they take carbon out of the atmosphere and sequester it or draw it down into the ocean.” She gives you the plain meaning right away: “draw it down.” Speakers in science documentaries often do this — a formal word appears, then a simpler phrase right after it explains what it means. The word comes from Latin, meaning “to place in safekeeping.” You will see it in three main areas. In science: “forests and oceans sequester carbon.” In law: “the jury was sequestered” — kept away from the public during a trial. In politics: “budget sequestration” means certain funds are locked away and cannot be spent. In all three areas the word is formal — you would not use it in everyday conversation. But in news articles, nature documentaries, and academic writing it comes up often, so it is good to know.